This invention relates to solid propellant compositions and to a novel family of plasticizers for use therewith. In a more specific aspect, this invention concerns itself with the use of a novel family of azido esters as energetic plasticizers for advanced solid propellant compositions. In still another specific aspect, this invention concerns itself with the use of azido esters as a means of reducing or minimizing the amount of flame in the exhaust gases generated during the operational phase of gun, missile and rocket propellants.
The increased utilization of propellant compositions for guns, rockets and missiles has spawned a considerable research effort in an attempt to improve their performance characteristics. Generally, solid propellants consist of one or more organic or inorganic oxidizers dispersed in a resinous binder matrix which may also function as a fuel. Typical oxidizers are ammonium perchlorate or HMX (cycloetetramethylene tetranitramine), both of which are well known in the art. Various resinous components, such as hydrocarbons, polyesters, polyurethanes and other like materials may serve as the binder/fuel matrix. A supplemental fuel component, such as finely powered aluminum, may be used also. Other additive components, such as anti-oxidants, burning rate modifiers, wetting agents, anti-foaming agents and plasticizers may be added to the propellant composition, if desired. Dibutylphthalate or triacetin are generally employed as inert plasticizers in combination with the resinous binder material.
In using solid propellants, however, a problem exists in that an undesirable amount of flame is often produced in the exhaust gases emanating from the burning propellant during propulsion. Excessive amounts of flame are extremely undesirable in the exhaust gases since this provides data which pinpoints the sites from which the guns, missiles or rockets are being fired. As a consequence, a continuing research effort has been maintained in an attempt to provide a propellant with a minimum amount of flame in the propellant's exhaust gases.
In furthering the research effort referred to above, it was unexpectedly discovered that a new family of azido esters could be employed as energetic plasticizers in the fabrication of reduced flame temperature gun propellant systems. These novel plasticizers replace the conventional inert plasticizers utilized in conventional composite propellants. The resulting propellant produces a minimum amount of flame during propulsion.